Automatic telephone system



H. P. CLAUSEN.

AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED MAR. 19, 1918.

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H. P. CLAUSEN.

AUTOMATlC TELEPHONE SYSTEM. APPLICATION FILED MAR. 19. I9I8- m venfor:

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UNITED STATES PATENT OFFICE.

HENRY P. CLAUSEN. OF MOUNT VERNON. NEW YORK, ASSIGNOR TO WESTERN ELEC- TRIC COMPANY, INCORPORATED. OF NEN YORK. N. Y.,.A CORPORATION OF NEW YORK.

AUTOMATIC TELEPHONE SYSTEM.

Application filed March 19, 1918.

To all "whom it may concern:

Be it known that I, HENRY P. CLAUsnN, a citizen of the United States, residing at Mount Vernon, in the county of WVestchester, State of New York, have invented certain new and useful Improvements in Automatic Telephone Systems. of which the foliowing is a full, clear, concise, and exact description.

This invention relates to telephone systems and more particularly to automatic systems in which subscribers lines are provided with impulse transmitting devices.

In automatic telephone systems of this character, it sometimes happens that the calling subscriber in removing his receiver from the switchhook or by accidentally operating the switchhook after the receiver has been removed therefrom, causes one or more momentary breaks in his line circuit, thereby transmitting impulses which cause the switches of the system to operate in the same manner as the impulses produced by the proper manipulation of the impulse transmitter.

The object of this invention is to provide means for preventing the operation of a switch by such accidental impulses.

One feature of this invention is the provision of means whereby the operating magnet of a switch cannot be initially energized until a predetermined interval after the line circuit is placedin the proper condition to cause an impulse to be transmitted to the operating magnet. According to this feature, after the first impulse of a series of impulses is transmitted, the operating magnet is then immediately energized as soon as the line circuit is placed in the proper condition to cause each of the remaining impulses of such series to be transmitted to the operating magnet.

In the drawing, Figs. 1 and 2 diagram- .matically represent preferred embodiment oi this invention as applied to a selector circuit and to a repeater circuit respectively and Fig. 3 shows an alternate method of accomplishing the desired result.

It 'is believed hat the invention will be more readily understood from the following description. I

When the subscriber at substation A removes the receiver from its switchhook a circuit is completed for operating the line finder switch, which is designated by the brushes 1, 2 3, to extend the calling Specification of Letters Patent.

Patented Jan. 17, 1922.

Serial No. 223,393.

line to the first selective switch shown in Fig. 1. A circuit is then closed from grounded battery, upper winding of relay 4, upper armatureand back contact of relay 5, brush apparatus at substation A, brush 2-, inner lower armature and back contact of relay 5, lower winding of relay 4 to ground. Bela 4 becomes energized and completes an energizing circuit for relay 6, from grounded battery through winding of relay 6. armature and front contact of relay 4 to ground.

The subscriber now operates his sending device 7 to interrupt the circuit of relay 4 a predetermined number of times. The sending device is arranged so that the first interruption of each series produced thereby is of longer durationthan the other interruptions'oi the same series. A sending device of this character is shown in applicants Patent No. 1,334,080 of March 16, 1920.

The relay 4 does not deenergize as soon as its circuit is opened by the sending device, due to a short-circuited winding which is normally included in a circuit from ground,

middle winding of relay 4, upper armature and back contact of relay 8 to ground. It

is well known in the electrical art, that the .reductlon of fiux'in the core of a relay caused by the opening of the line circuit induces a current in such a short-circuited winding and retards the retraction of its armature. The middle winding is, however, designed so as to allow the relay 4 to deenergize only after a predetermined period in response to the first impulse which is of comparatively long duration. The period for which the relay4 is deenergized by this first long interruption of the line circuit is of the same duration as that which is produced by the succeeding impulses of the series as hereinafter described. It will, therefore, be obvious that any momentary interruptions produced in the line circuit will not cause the line relay 4 to deener ize, due to this normally closed circuit.

The deenergization of relay 4, in response to the first impulse completes a circuit from grounded battery through winding of primary magnet 9,. winding of relay 8, lower armature and front contact of relay 6, lower armature and back contact of relay 5, lower armature and back contact of relay 4 to ground, thusenergizing magnet 9'and relay 8. Relay- 8 when energized, opens at its upper armature the circuit of the middle winding of relay 1-, thus allowing relay to. respond to succeeding short interruptions of the line circuit. The energization of magnet.

9 move the first selector switch one step in its primary movement. In a similar manner, magnet 9,-in' response to each succeeding interruption produced in the line circuit, is energized and moves the selector switch another step in its primary movement.

- V Relays 6 and 8 are made slow to release-so that their armatures remain attracted during the interruptions produced in their circuits during the transmission of the impulses.

When relay 8 responds to this series of impulses, a c rcuit is completed from grounded battery through the winding of relay 10, lower armature and front contact of relay 8 to ground. Relay 10 becomes energized and completes a locking circuit for itself from grounded battery, through winding of relay 7 10, armature and front contact of relay 10,

conductor 11, primary off normal contact 14, conductor 13, left armature and back contact of secondary magnet 12, upper armature and front contact of relay 6 to ground.

After the last impulse of the first series has been transmitted, the relay le-remains en- 'ergized and the slow-to-release relay 8 deenergizes, thus closing a circuit from grounded battery through winding of secondary magnet 12, right armature and back contact of magnet 12, backcontact and lower.

armature ofrelay 8, armature and front contact of relay 10 to ground over the circuit previously described for relay 10. The

- energization of the magnet 12 moves the brushes 15, 16 and 17 of the selector switch into engagement with the terminals of the and back contact of magnet 12, another circuit is completed therefor through the test brush 15. If the first trunk is busy, ground will be found upon the test terminal 18 thereof, and the'relay 10 will be held energized, due to a circuit from grounded battery through winding of relay 10, armature and front contact of relay 10, test brush 15, test terminal 1S, to ground. As soon as the I secondary magnet has fully attracted its armatures, it interrupts its own circuit, whereupon it immediately deenergizes. It 1s then again energized to step the brushes 15, 16, and y 17 into engagement with the termlnaljs of the second trunk of theselected group; If this trunk is busy, the brushes are moved'into engagement with the terminals of a third trunk 18 to mark this trunk as busy to other hunting selectors over the circuit previously traced to the contact of the upper armature of relay 6.

Thedeenergization of relay 10 also completes a circuit from grounded battery through winding of relay 5, armature and back contact of relay 10, to ground at the up- 61 armature and front contact of relay 6. elay 5 becomes energized and by attracting its armatures disconnects the calling line from relay 4 and extends it through the idle trunk. r 7 It will be assumed in the present description that the trunk seizedby the first selector switch extends to a second selector switch whose circuits are not arranged to receive a long first impulse such as is produced by the sending device 7. It is, therefore, necessary to translate this first long impulse of each seriesproduced by the sending device 7 into one of the same duration as all the other impulses of the same series. This translation is produced by the repeater-which is inserted in the trunk.

When the relay 5 is energized a circuit. is

completed for the line relay 21 of therepeat-er associated withthe idle trunk, this circuit being traced from grounded battery through upper winding ofrelay-21, conductor 23, terminal 2O, brush. 17, front contact and upper armature of relay 5, brush 3, apparatus at substation A, brush 2, inner lower armature and frontcontact of relay 5, brush 16, terminal 19, conductor 2a, lower winding of relay 21 to ground. Re lay 21 becomes energized and closes a circuit for relay 26, from grounded battery, winding of relay 26, upper armature and front contact of relay 2]. to ground. Relay 26, by attracting its upper armature, places ground upon the test terminal 18 associated therewith, replacing the ground originally placed thereby relay 6, to render it nonsele'ctable by any first selecto switch, and also to maintain the relay 5 energized. Since relay 6 is made slow to release its armatures, the original energizing circuit of relay 5 is maintained for a sufficient length of time,

after the relay 5 transfers the line circuit from relay 4 to relay 21, to allow relays 21 and 26 to energize and establish this substitute circuit for relay 5 through the test brush 15. 1 7

Relay 26. also .completesa circuit from grounded battery, winding of relay 22, up

per armature and front contact of relay 26 to ground. Relay 22 becomes energized and connects both sides of the outgoing end of the trunk together through brush 28, upper armature and front contact of relay 22, upper armature and back contact of relay 31, resistance 36, inner lower armature and back contact of relay 31, lower armature and front contact of relay 21, lower armature and front contact of relay 22 to brush 29. The second selector switch which is designated by the brushes 28, 29 and 30 is thereby placed in readiness for the second series of impulses.

In response to the first impulse of thesecond series, which. is a long. interruption of the circuit of relay 21, relay 21 does not deenergize immediately, due to its short-circuited winding which is included in a circuit from ground, middle winding of relay 21, lower armature and back contact of relay 3 to ground. Relay 21, however, does deenergize after a short interval and opens, the outgoing circuit to the second selector switch for a period equal in length to the succeeding interruptions which constitute this series of impulses to cause said switch to function in the well-known manner. At the same time a circuit is completed from grounded battery through winding of relay 31, lower armature and front contact of relay 26, upper armature and back contactof relay 21 to ground. Relay 31 becomes energized and opens the circuit through the middle winding of relay 21., thus allowing the succeeding impulses to be repeated in their natural length. Relay 31 is made slow to release and therefore maintains this last mentioned circuit open during the transmission of the remaining impulses of the second series.

It is believed that it is so obvious to one skilled in the art that relays 21 and 31 will control in a similar manner the translation of the first long impulse of each of the remaining series of impulses transmitted in completing a call to the substation B, that further description of the establishment of a connection is deemed unnecessary.

When the calling party'replaces the re ceiver on its switchhook, relay 21 becomes deenergized and after a short interval the slow-to-release relay 26 deenergizes and removes ground trom the test terminal 18. Relay 5 deenergizes and closes a circuit from grounded battery, winding of release magnet 37, primary otl normal contact 38, lower armature and back contact of relay 6, lower armature and back contact of relay 5, lower armature and back contact of relay 4 to ground. Release magnet 37 becomes energized and restores the first selector switch to normal. 'I he line finder switch is returned to its normal position in any well-known manner.

he deenergizat-ion of relay 26 also opens the circuit of relay 22, which in turn deenergizes and opens the circuit leading to the second selector switch. The second selector switch and the remaining switches used in establishing the connection to substation B may then be released in any well-known manner.

In Fig. 3 a modification ot' a portion of the selector switch circuit of Fig. 1 is shown. Only enough of the selector circuit is shown as is deemed necessary "for a clear understanding of its operation. It will be assumed that the calling substation A has been extended to the selector switch and that the subscriber is sending out the first series of impulses.

In response to the first interruption a circuit is closed from grounded battery through. the upper armature and back contact ot' relay 8, winding of relay 8, lower armature and front contact ot slow-tc-release relay (3, lower armature and back contact of relay 5, lower armature and back contact oi relay l to ground. Due to this first interruption in the line circuit being of long duration, .he above traced circuit for relay 8 maintained long enough to allow it to attract its armatures which are weighted to make them slow to pull up. Relay 8 by attracting its upper armature opens its original energising circuit and at the same time removes a shunt from around the winding of the primary magnet 9, which becomes energized and moves the first selector switch one step in its primary movement. The energizing circuit of magnet 9 is traceable from grounded battery, through winding of magnet 9, winding of relay 8, lower armature and front contact of relay 6, lower armature and back contact of relay 5, lower armature and back contact of relay 4 to ground. In response to each succeeding interruption produced in the line circuit the magnet 9 moves the selector switch another step in its primary movement until the desired group of trunks is reached. Relays 6 and 8 are made slow to release so that their armatures remain attracted during the interruptions produced in their circuits during the transmission of the impulses. Relays 8', by holding its upper armature attracted, maintains the shunt around the winding of magnet 9 open and therefore removes the necessity of any more long impulses alter the first one has been transmitted.

lVhat is claimed is:

1. In a telephone exchange system, a line circuit, an automatic switch, impulse sen-d ing means, a line relay controlled by said impulse sending means, an operating magnet for said switch, a circuit for said magnet controlled by said relay, means for rendering said relay slow to retract its armatures, and means operated by the first deenergization of said relay for rendering said last mentioned means ineffective.

2. In a telephone exchange system, a line circuit, an automatic switch, impulse sending means, a line relay controlled by said impulse sending means, an operating magnet for said switch, a circuit for sald magnet controlled by said relay, a clrcuit including a winding of said relay for ren-' dering said relay slow to retract its armatures, and means operated by the first deenergization of said relay for opening and maintaining said last mentioned circuit opened While said relay is being controlled by said impulse sending means.

3. In a telephone exchange system, a line circuit, an automatic switch, impulse sending means, a line relay arranged to be deenergized by impulses produced by said impulse sending means, an operating magnet for said switch, a sloW-to-release relay, a circuit including a second Winding of said line relay for rendering said line relay slow to retract its armatures, a circuit for said operating magnet and said sloW-to-release relay closed by the initial deenergization of said lin relay, and means controlled by said slow-t0- release relay for opening the circuit including the second mentioned Winding of said line relay.

4. In a telephone system, a line circuit, means for producing a series of variations in the normal flow of current through said line circuit, the first of each series of variations being maintained for a different duration of time than the succeeding variations of each series, and means operated by each series of variations during the production thereof for transmitting a series of impulses of only one duration.

5. In a telephone system, aline circuit, means for producing a series of variations in the normal How of current through said line circuit, the first or" each series of variations being maintained for a different duration of time than the succeeding variations of each series, repeater arrangements operated by said series of variations during the production thereof for transmitting a series of impulses of only one duration, and selector switches responsive to said series of impulses.

In witness whereof, I hereunto subscribe my namethislQth day of March, A. D., 1918.

l-IENRY P. CLAUSEN. 

